The formulator of a manual dishwashing detergent composition is required to formulate compositions which meet a number of consumer relevant performance demands.
Firstly, such a composition should be effective at removing soils from dirty "dishes" when used in a manual dishwashing process. The soils encountered in dishwashing are largely but not exclusively food based. Particularly difficult soils to remove include greasy soils, burnt-or baked-on soils or those which have been allowed to harden onto the dish article, as well as non-food soils such as lipstick on the rims of glasses or nicotine stains.
Once the soils have been removed from the dishes the dishwashing detergent should act so as to suspend these soils in the wash solution and thus prevent their redeposition onto the dishes, or onto the surface of the sink.
In addition, the manual dishwashing composition should be high sudsing and the sudsing should persist throughout the washing process. This is particularly important as sudsing is used as an indicator by the consumer of the performance of the detergent composition. Moreover, the consumer also uses the sudsing profile as an indicator that the wash solution still contains active detergent ingredients and the consumer usually renews the wash solution when the sudsing subsides. Thus, a low sudsing formulation will tend to be replaced by the consumer more frequently than is necessary because of the low sudsing level.
The manual dishwashing composition should also be mild to the skin, and particularly to the hands and should not cause skin dryness, chapping or roughness. Such skin complaints largely result from the removal of natural oils from the skin. Thus, the manual dishwashing composition should desirably be effective at removing grease from plates but not natural oils from the skin.
In order to address the consumer demand for effective removal of soils found in a dishwashing load, particularly greasy soils, liquid detergent compositions may comprise certain co-surfactants such as long chain amine oxides, betaines, non-bridged polyhydroxy fatty acid amides and branched alkyl carboxylates, which have been found particularly effective in the removal of such soils, especially when present in high concentrations. However, a disadvantage of such compounds is their tendency to reduce the overall sudsing profile of the detergent composition.
Thus, it is an aim of the present invention to formulate a dishwashing composition which facilitates the removal of soils, especially oily and greasy soils and which produces a high and persistent level of sudsing.
It has now been found that this objective can be achieved by the incorporation of certain bridged polyhydroxy fatty acid amides into liquid dishwashing detergent compositions comprising long chain amine oxides, betaines, polyhydroxyfatty acid amides, alkyl carboxylates or mixtures thereof. Furthermore, an additional advantage of the present invention is that the suds level produced by the addition of the bridged polyhydroxy fatty acid amides is greater than the sudsing produced by conventional suds boosters such as shorter chain length amine oxides.
Polyhydroxy fatty acid amides have been disclosed as surfactants in the art, see for example U.S. Pat. No. 5,194,639, U.S. Pat. No. 5,174,927 and U.S. Pat. No. 5,188,769.